This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall goal of this project is to determine ovarian contribution to the circulating levels of delta-like 1 homolog (DLK1), a peptide factor that regulates adipocyte and osteoblast development. While several studies have implicated ovarian steroids, particularly estradiol, in the regulation of female adiposity and bone density, protein hormones of ovarian origin involved in these processes are poorly understood. Based on preliminary data demonstrating that the primate ovary is one of a limited number of tissues expressing DLK1, studies were designed to determine if the significant levels of DLK1 found in the circulation of female macaques originates from, or are regulated by, the ovary. Rhesus macaques will be used in this project as they serve as excellent experimental surrogates for women because of their similar hormonal profiles and ovarian cycle lengths.